1. Field
Example embodiments relate to a photoluminescence liquid crystal display (LCD). Other example embodiments relate to a photoluminescence LCD having a simpler panel structure and an increased efficiency in use of light by employing a light source emitting polarized light.
2. Description of the Related Art
An LCD may include a liquid crystal panel formed by injecting a liquid crystal between two substrates having field generating electrodes. An electrical field may be generated by a predetermined or given voltage applied to the electrodes. The generated electrical field may arrange liquid crystal molecules so that light passes through the arranged molecules. The LCD may display images by modulating the transmitted light.
An LCD may further include a backlight unit and a liquid crystal panel. The backlight unit may include a lamp, a lamp holder, a light guide plate, a reflection sheet, and a diffusion sheet. The liquid crystal panel may include the liquid crystal, polarizers, transparent electrodes, a thin film transistor (TFT) panel, and a color filter. Light emitted from the lamp may be weakened while passing through each optical component constructing the LCD and then may be used to illuminate a front surface portion of the liquid crystal panel.
FIG. 1 is a graph illustrating light loss ratio in each component in a conventional LCD. When studying the light loss ratio at each optical component, most light loss occurs at the color filter and the polarizer. For displaying a color image, a conventional LCD may use a color filter that may include a set of red R, green G, and blue B regions corresponding to each pixel. In an LCD with a color filter, each color region of the color filter may transmit light having a wavelength corresponding to its color. Only one third of the total light (white light) may be used for displaying an image. The light loss ratio may be at least about 67% at the color filter.
The liquid crystal panel generally may include a rear substrate, a front substrate, a liquid crystal layer, a rear polarizer, and a front polarizer. The liquid crystal layer may be formed between the rear substrate and the front substrate. The rear polarizer may be disposed on an outer surface of the rear substrate to transmit light having a specific polarization direction to the liquid crystal layer. The front polarizer may be disposed on an outside surface of the front substrate. For example, a general LCD may include two sheet type polarizers having a thickness of about several tens to about several hundreds of nanometers. Because only the light that passes through the rear polarizer is incident on the liquid crystal layer, light transmission efficiency may be less than about 50% when a light source emitting unpolarized light is used. A conventional LCD may display an image using only about 3% of the total amount of light emitted from a light source. For example, the conventional LCD may have a decreased light use efficiency.